Blister pack
A blister pack[1] is any of several types of pre-formed plastic packaging used for small consumer goods, foods, and for pharmaceuticals.
Blister packs are useful for protecting products against external factors, such as humidity and contamination for extended periods of time.
Many blister packaging machines use heat and pressure via a die to form the cavity or pocket from a roll or sheet of plastic.
In recent years, improvements in cold forming—specifically allowing steeper depth/angles during forming, which minimizes the amount of material used for each cavity—have helped this technology increase.
The main advantages of the plastic-based blister pack are its more compact size compared to cold formed aluminum and its transparency to see the product.
Blister packs can provide barrier protection for shelf life requirements, and a degree of tamper resistance.
In other parts of the world, blister packs are the main packaging type since pharmacy dispensing and re-packaging are not common.
In some parts of the world the pharmaceutical blister pack is known as a push-through pack (PTP), an accurate description of two key properties (i) the lidding foil is brittle, making it possible to press the product out while breaking the lidding foil and (ii) a semi-rigid formed cavity being sufficiently collapsible to be able to dispense the tablet or capsule by means of pressing it out with the thumb.
Blister packs are created by means of a form-fill-seal process at the pharmaceutical company or designated contract packer.
A form-fill-seal process means that the blister pack is created from rolls of flat sheet or film, filled with the pharmaceutical product and closed (sealed) on the same equipment.
There are two types of blister machine' design: rotary and flat-plate, depending on the mechanism for sealing the lidding foil.
The thermoformed base web is made of a thicker plastic sheet, generally between 500 and 1,000 μg and can not be collapsed, thus forming a solid tray.
The lidding film provides a peel-open feature and is generally porous to allow sterilization (such as the Dupont medical Tyvek material).
In case of difficult shapes, the warm film will be physically pushed down partially into the cavity by a "plug-assist" feature.
[clarify] In the case of cold forming, an aluminum-based laminate film is simply pressed into a mold by means of a stamp.
The principal advantage of cold form foil blisters is that the use of aluminum offers a near complete barrier for water and oxygen, allowing an extended product expiry date.
[citation needed] In a thermo cold forming process, the first packing is done by thermoforming technique, after which the product is repacked with a cold-formed package.
In the absence of plasticizers, PVC blisters offer structural rigidity and physical protection for the pharmaceutical dosage form.
The European Pharmacopoeia (Ph Eur) references the requirements for PVC blister packs for pharmaceutical primary packaging in the monograph EP 3.1.11 "MATERIALS BASED ON NON-PLASTICISED POLY(VINYL CHLORIDE) FOR CONTAINERS FOR DRY DOSAGE FORMS FOR ORAL ADMINISTRATION".
WVTR values of commercial cyclic olefin-based pharmaceutical blister films typically range from 0.20 to 0.35 g/m2 per day at 38 °C (100 °F) and 90% RH.
The most common lidding foil with push-through features is 20 μm hard tamper aluminum, which can be supplied pinhole-free from the producers.
Blister packaging allows either the manufacturer or retailer to include promotional materials or advertisements to help build a brand and increase customer loyalty.
[citation needed] To prevent retail theft, packages are specifically designed so that the customer cannot "touch and feel" the product.
A tamper-evident package, according to the regulations of the Food and Drug Administration (21 CFR § 211.132), "is one having one or more indicators or barriers to entry which, if breached or missing, can reasonably be expected to provide visible evidence to consumers that tampering has occurred".
